Tropical Storm Isaias sputters in the Bahamas, approaches Florida overnight, then hits the east coast

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  • Conditions in Florida are slowly deteriorating in Florida.
  • Tropical storm conditions are expected in southern Florida on Sunday.
  • Then scratch the coast of Florida until Monday morning.
  • It will then head to the Carolinas later Monday and Monday evening in the form of a tropical storm.
  • The tropical storm will then cross the northeast from Tuesday to Wednesday.

Isaias (ees-ah-EE-ahs) heads for the east coast of Florida, now as a tropical storm, before moving up the east coast all the way north to New England in the first half of the week to come.

Winds have eased slightly at Isaias since Saturday afternoon as the storm battles dry air and windshear, and attempts to recover from the interaction with Andros Island in the Bahamas.

Watches, Warnings and Current Conditions

A hurricane warning is in effect from Boca Raton to the Flagler / Volusia County line in Florida. A hurricane warning means hurricane conditions are expected in the warning area within 36 hours.

(PLUS: Hurricane season terms you should know)

Hurricane warnings continue in the northwestern Bahamas, including Grand Bahama.

Tropical storm warnings are in effect from the northern Florida Keys to Boca Raton and the interior / north to Orlando, Florida, including Lake Okeechobee. They also extend from the Volusia-Flagler County line to Ponte Vedra Beach, Florida.

A tropical storm watch has extended north to the South Santee River in South Carolina and continues to extend south to Ponte Vedra Beach, Florida.

In addition, a storm surge watch was issued from Jupiter Inlet at Ponte Vedra Beach. This means that there is a possibility of potentially fatal flooding due to rising waters moving inland over the next 48 hours.

Watches and warnings

(A watch is issued when tropical storm or hurricane conditions are possible within 48 hours. A warning is issued when such conditions are expected within 36 hours.)

The center of Isaias moved north to Andros Island, northwest of the Bahamas, on Saturday afternoon, where a gust of 69 mph was measured by a US Navy site. Heavy thunderstorms persist in the northern Bahamas, inundating Grand Bahama.

Strong winds swept through southern Florida as Isaias slowly approached. Sites on the south coast of Florida reported wind gusts of between 40 and 100 km / h early Saturday evening, including a report of a gust of 59 mph near Dania Beach, in Florida. Winds have been gusting across southern Florida since the first band of rain.

Current satellite, radar and winds

Latest forecast

Here is our latest forecast trajectory, from the National Hurricane Center, which includes temporary strengthening of Isaias to hurricane force overnight.

Current information and planned path

(The area shaded in red indicates the potential path to the center of the system. It is important to note that impacts (especially heavy rains, heavy waves, coastal flooding, winds) with any tropical cyclone usually spread beyond its intended path. .)

There are still significant uncertainties.

First, Isaias struggles powerfully against the two nemeses of dry air and wind shear, the change in wind speed and / or direction with height, despite abundant warm water in its path.

NOAA hurricane chasers recently discovered that desert air was lurking west and southwest of the Isaias Eye Wall with humidity values ​​as low as 3% at 25,000 feet. . Strong upper winds from the west and southwest blow this dry air into the circulation of Isaias, keeping it unbalanced and disorganized.

We don’t expect much significant strengthening, but it could regain hurricane status on Saturday night.

Current satellite, analysis of wind shear and water temperatures

(Areas of cloud are shown in white. Areas of strong windshear, the difference in wind speed and direction with height, are shown in dark purple. Strong windshear is hostile to mature tropical cyclones and those trying to grow. Water temperature is shown in red and with numbers in degrees, anything above 80 degrees is favorable for development.)

The next question now is how close the center of Isaias is to Florida’s Atlantic coast from Saturday night to Sunday night. The strongest winds usually occur in a band of convection near the center, known in a hurricane as the eye wall.

Florida residents will recall that the much stronger and also larger Hurricane Matthew eyewall stayed just offshore as it moved north parallel to Florida’s east coast. Much of the east-central Florida coast received wind gusts of 60 to 80 mph, but Cape Canaveral, a section of land that juts out less than 15 miles into the Atlantic, received wind gusts well above 100 mph. These stronger winds have cost NASA’s Kennedy Space Center millions of dollars.

These types of winds are unlikely in Isaias, but the general idea remains: stronger winds could strip the coast.

It is the difference between being in the eye wall of a hurricane and just outside the eye wall.

For now, we expect there is a good chance that Isaias will pass close enough to scratch at least part of the Atlantic coast of Florida, where hurricane warnings are in effect.

After that, the forecast path will rely heavily on the directional elements in the atmosphere – the altitude of Bermuda and an upper level drop in wind flow over the Mississippi Valley.

Leadership factors at play

(The summit of Bermuda and an upper-level trough above the Mississippi Valley may help guide the system in the southeastern United States, assuming it survives that far. The potential forecast path of the National Hurricane Center is marked in red.)

Isaias is expected to make a turn north and then northeast from Monday.

From there, it could pass near the Carolinas Monday through Tuesday as a tropical storm, then quickly sweep near parts of the northeast coast as far north as New England Tuesday through Wednesday.

(PLUS: Depth forecast for the central Atlantic and northeast)

Potential impacts

Vent

As mentioned earlier, Isaias produces strong gusts of wind and bands of heavy rain over the northern Bahamas and increasingly into southern Florida.

Current wind field

(The orange circle shows the extent of tropical storm force winds in the system (at least 39 mph). The purple circle indicates the extent of hurricane force winds (at least 74 mph), according to the National Hurricane Center.)

Tropical storm conditions are expected to arrive and become more persistent early Sunday morning in southern Florida, and arrive Sunday afternoon in central Florida.

Keep in mind that the winds will be strongest near the coast and in tall buildings.

(The times shown show that winds of at least 40 mph are expected for a given community with a higher chance of seeing those winds shown in red and purple.)

Here’s what the wind field could look like in 12 hours with the strongest gusts hitting the Florida coast.

Storm surge

A dangerous storm surge is possible along the east coast of Florida and in the Bahamas.

A dangerous storm surge of up to 3 to 5 feet above ground level is forecast from the National Hurricane Center, in areas where winds will blow on the coast in the northwestern Bahamas.

Storm tide watches were issued from Jupiter Inlet to Ponte Vedra, Florida, where a storm surge of 2 to 4 feet, above ground, is possible if a peak wave occurs at the time of the tide high. A 1 to 3 foot storm surge can occur from North Miami Beach to Jupiter Inlet.

The highest tides of greatest concern are Sunday morning in South Florida and Sunday evening further along the Florida coast.

Storm surge forecast

(Data from the National Hurricane Center)

The swells generated by Isaias arrive along the southeastern coast of the United States, causing high waves and the danger of rip currents. The surf will remain high for the entire duration until the passage of Isaias.

Rain floods

It appears that Isaias could be loaded eastward in terms of precipitation regime, meaning that much of its precipitation could be over the Atlantic rather than Florida. This trend is expected to change as Isaias moves north.

Rainfall of 4 to 8 inches is likely in parts of the Bahamas with up to 4 inches in parts of Cuba. Flash floods and potentially fatal landslides are possible.

Two to four inches of rain is possible in east-central Florida through Monday, with isolated maximum totals of 6 inches, according to the National Hurricane Center.

Heavy rains can also spread to the Carolinas and the mid-Atlantic from Monday to Wednesday.

To learn more about the possible impacts in the Mid-Atlantic and Northeast, read our latest discussion here.

Precipitation forecast

(This should be interpreted as an overview of where the heaviest rains can fall and can move depending on the predicted path of the tropical cyclone. Higher amounts can occur when bands of rain stagnate. over a period of a few hours.)

History of the storm

Isaias is the earliest named ninth Atlantic tropical cyclone on record. The previous record was Irene on August 7, 2005.

Typically, the ninth named tropical system occurs in the Atlantic Basin in early October, meaning this year’s pace is more than two months ahead of average.

(PLUS: Atlantic hurricane season 2020 is at an all-time high)

Heavy rains caused severe flash flooding in several parts of Puerto Rico. Just under 4.5 inches of rain was measured in San Juan on Thursday.

Numerous fallen trees, landslides and flooding have been reported in southwest Puerto Rico, according to local emergency management. Flooding of the river was recorded by USGS gauges at several locations in Puerto Rico.

(NEWS: Murderous Isaias caused extensive damage in the Dominican Republic, Puerto Rico)

Heavy rains and high winds move away from New Providence Island, including the capital of the Bahamas, Nassau. A 50 mph gust of wind was timed at Nassau International Airport, and power was cut in parts of the island as a precaution.

(RECENT NEWS: Impacts of Isaias in the Bahamas)

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The Weather Company’s primary journalistic mission is to report on the latest weather news, the environment and the importance of science in our lives. This story does not necessarily represent the position of our parent company, IBM.

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